Spring device for drilling machines



July 5,' 1938.

A. HOSSFELD SPRING DEVICE FOR DRILLING MACHINES Filed May 3, 1937 2 Sheets-Sheet l July 5, 1938. HQSSFELD 2,123,048

SPRING DEVICE FOR DRILLING MACHINES Filed May 3, 1937 2 Sheets- Sheet 2 Even/0 x" MM We?! Patented July 5, 1938 UNITED STATES PATENT OFFICE SPRING DEVICE FOR. DRILLING MACHINES Albert Hossfcld, Winona, Minn. Application May 3, 1937, Serial No. 140,335

6 Claims.

My present-invention relates to drilling machines of the type disclosed and broadly claimed in my United States Letters Patent No. 1,888,668 issued of date November 22, 1932. In this type of drilling machine, the drill is mounted on a reciprocating carriage for endwise reciprocating movement that is independent of the reciprocating movement of the carriage. A pair of compression springs is provided for reciprocating the drill at a greater speed than that of the carriage. One of these springs acts as a propelling spring for the drill to produce its operative stroke and the other of said springs acts as a buffer spring for the drill. The propelling spring is placed under tension by the drill during its return stroke and drives said drill by its expanding movement at a high velocity during its operative stroke. The buffer spring is placed under tension by the drill during its operative stroke and its expanding movement returns or retracts the drill at a high velocity. Due to the high velocity at which the drill is operated, the lives of ordinary propelling and buffer springs are relatively short.

The objection to the propelling spring was overcome by substituting therefor a novel spring device disclosed and broadly claimed in my United States Letters Patent No. 1,930,098 of date October 10, 1933, and entitled Spring device for drilling machines.

It is now the object of this invention to provide novel means for increasing the life of the buffer spring and facilitate the application thereof to the drilling machine or the removal of the same therefrom.

To the above end, generally stated, the invention consists of the novel devices and combinations of devices hereinafter described and defined in the claims.

In the accompanying drawings, which illustrate the invention, like characters indicate like parts throughout the several views.

Referring to the drawings:

Fig. 1 is a fragmentary perspective view of .a drilling machine having the invention embodied therein;

Fig. 2 is a fragmentary detail View partly in front elevation and partly in central vertical section;

Fig. 3 is a view principally in plan showing the buffer spring device, lower cross-head and its suspending rods removed from the drilling machine;

Fig. 4 is a View partly in front elevation of the parts shown in Fig. 3;

Figs. 5 and 6 are detail views with some parts sectioned on the lines 5-5 and 66 of Fig. 4;

Figs. '7 and 8 are views of the parts shown in Fig. 5 separated the one from the other;

Fig. 9 is a view corresponding to Fig. 4 with the exception that the spring has been contracted sufiiciently to permit the removal of the post sections and its spring cap from the post; and

Fig. 10 is a view corresponding to Fig. 9 with the exceptionthat the post section and spring cap have been removed from the post.

The drilling machine fragmentarily illustrated in the drawings is fully shown, described, and broadly claimed in Patent No. 1,888,668 heretofore fully identified.

Of the parts of the drilling machine shown, it is important to note the drill II, the main frame I2, the carriage I3, the tilting frame I4, the connecting rods I5 for reciprocating the carriage I3 on the frame I4, the drill propelling spring device I6, the buffer spring I1, and the friction grip I8. The drill I I includes a body I9 in the form of a long round steel rod and a cutter 20 on one end of said body. This drill I I is mounted on the carriage I3 for compound reciprocatory and rotary movements.

The tilting frame I4 includes a pair of laterally spaced guide posts 2| and a pair of cross-tie plates 22 rigidly secured thereto and held laterally spaced thereby, the one from the other. A striker plate 23 for the grip I8 rests on the crosstie plates 22 and is rigidly secured thereto.

The carriage I3 includes an upper cross-head 24 slidably mounted on the posts 2|, a lower cross-head 25, and a pair of rods 26 which hold said lower cross-head suspended from the upper cross-head 24 between the cross-tie plates 22. The drill II extends axially through the spring device I6 and the buffer spring IT, and which spring device I6, at its outer end, is attached to a rotatable bearing 21 on the cross-head 24 and is oscillated during reciprocatory movement of the carriage I 3 by connectionsZB fromv said bearing to the tilting frame I4.

Obviously, the bearing 21, and hence the upper cross-head 24, affords a base of resistance for the spring device I6 and the buffer spring I! rests on the lower cross-head 25 which affords a base of resistance therefor. The friction grip I8 is mounted on the drill body spring device I6 and the buffer spring I1, and normally rests on said buffer spring .and supports the drill II therefrom with the grip I8 above the striker plate 22 and normally out of contact therewith.

I9 between the Operation of the drilling machine thus far described may be briefly described as follows, to wit:

As the carriage l3 starts its upward travel the compressed buffer spring I! expands against the grip I 8 and gives the drill H a powerful upward throw which causes the same to travel at a much faster speed than the speed of the carriage. During this upward travel of the drill II, the grip l8 engages the spring device 16, compresses the same under powerful tension and at which time the spring device l6 absorbs the shock of the drill H and brings the same to a stop at the limit of the upward travel of the carriage I3. Downward movement of the carriage l3 gives the drill i I a powerful downward throw which is accelerated by the expansion of the compressed spring device l6 and causes the drill H to attain a high velocity as it travels to its work. At or practically at the end of the downward stroke of the drill H the grip I8 is brought to a stop by its engagement with the striker plate 22 and as the drill H advances into the rock, it drives itself through the grip 18 by the force of its momentum. The feeding of the drill H through the grip l8 takes place at a series of almost imperceptible steps of movement. During the operative or downward stroke of the drill II, the grip l8 engages the buffer spring I1 and places the same under tension.

For the purpose of this case it is not thought necessary to describe in detail the rotary movement imparted to the drill I l except to state that during the upward travel of the carriage l3 and while the grip H3 is in engagement with the spring device l6, said spring device is given a turning movement by connections 28 which imparts a like movement to said drill by frictional engagement between the spring device l6 and the grip [8.

Referring now in detail to the present invention which includes the buffer spring 11, it has been found in actual operation of the drilling machine that when the buffer spring I! was allowed to exert its full expanding force on the upwardly moving drill II, that the life of said spring was comparatively short due to the final stretching movement thereof during each return stroke of said drill.

It has also been found that by limiting the expanding movement of the buffer spring I! that the life thereof was materially increased. As one means for limiting the expanding movement of the buffer spring I1, I provide a tubular post 3- 29 which extends axially through a central passageway 39 in the lower cross-head with freedom for endwise sliding movement. This post 29, above the lower cross-head 25, extends axially through the buffer spring I! and has on its lower end an annular shoulder 3| which engages the under side of said cross-head as a stop that limits the upward movement of said post through the cross-head 25. Removably applied to the upper end of the post 29 is a spring cap 32 which overlies the upper end of the buffer spring I! and holds the same compressed between said cap and the cross-head 25.

Formed with the spring cap 32 is a depending post section 33 axially aligned with the post 29 and forming an extension thereof. The post 29, at its upper end portion, is bifurcated to afford a pair of upstanding prongs 34 each of which has at its upper end a pair of oppositely projecting lugs 35. The post section 33 is also bifurcated to afford a pair of depending prongs 36 which extend between the prongs 34. Each prong 36 has on its lower end a pair of oppositely projecting lugs 31. It will be noted that the lugs 31 underlie the lugs and are held in engagement therewith by the buffer spring I! which is held compressed between the lower cross-head 25 and the spring cap 32.

By reference to Figs. 5 to 8, inclusive, it will be noted that the post section comprising the prongs 34 and 38 and the lugs 35 and 31 has the same external diameter as the post 29 and that the buffer spring H, which encircles the post 29 and the post section 33, holds said section axially aligned with the post 29. By compressing the buffer spring ll so that its upper end is below the post section 33 said section and spring cap 32 may be removed from the post 29 by a radial movement thereof relative to the post 29 to separate the prongs 35 from the prongs 34 and the lugs 37 from the lugs 35. After the spring cap 32 is removed from the post 29 and the tension on the spring l'l released, said spring and post may readily be removed from the carriage As a novel means for compressing the spring ll to permit the application of the spring cap 32 to the post 29 or the removal of the same therefrom, I provide a pair of collars 38 and a pair of nut-equipped draw-bolts 39. Each collar 38 has an internal recessed annular seat 40 adapted to receive the upper convolution of the spring ll, outwardly of the spring cap 32, or the stop flange 3!. On the perimeter of each collar 38 is a pair of diametrically opposite apertured lugs 4| through which the bolts 39 extend.

It will of course be understood that any other suitable means may be used to compress the buffer spring H. To apply the buffer spring device to the lower cross-head 25, the same must be done before said cross-head is placed in the drilling machine, or, in case the spring I! breaks or it is necessary to remove the same, the lower cross-head 25 must be removed from the drill machine by detaching its suspending rods 26 from the upper cross-head 24.

It may be assumed that it is necessary to remove the buffer spring device from the lower cross-head 25, and in which case the spring compresser 3839 is applied to said device as shown in Fig. 4. With the spring compressor thus applied, the nuts on the bolts 39 are turned thereon to draw the upper collar 38 toward the lower collar 38 and compress the spring I? to a point in which the top of the upper collar 38 is below the inner end of the post section 33, see Fig. 9. In this position of the upper collar 38 the post section 33 may be detached from the post 29 by a relative radial movement, see Fig. 10. After the post section 33 is removed from the post 29, the spring compressor is operated to release the tension on the spring Ill and thereafter removed from said spring.

From the above description it is evident that the post 29 and the post section 33 will limit the expanding movement of the spring I! and at the same time prevent stretching of said spring during its operative movement to retract the drill II. At the time the grip l8 strikes the spring cap 32, during the working stroke of the drill H which places the spring i'l under tension, the post section 33 will be moved thereby axially relative to the post 29 until the play between the post section and post has been taken up and thereafter the engagement of the post section 33 with the post 29, during further compression of the spring II, will move said post axially through the aperture 30 in the lower cross-head 25..

It may be here stated that it is highly important that the top portion of the structure holding the spring I! under compression be very light in Weight so that when the same is hit by the grip I8 carried by the drill II, which is moving at a very high velocity, the impact will not be sufiicient to break down the structure of the grip l8, which is preferably made from fibre.

The aperture in the striker plate 23 is just large enough to permit the spring IT to work freely therein and cannot be enlarged for the reason that the surrounding area is necessary to afford a striking surface for the grip l8. In view of this structure it will be seen that the embodiment of the device for holding the spring I! under tension within the external diameter of the spring I1 is necessary.

The invention described has in actual usage proven that it is possible to easily replace a bio-- ken buffer spring on the job with comparatively little work and expense.

What I claim is:

1. A spring device comprising a post having at one end a spring base and at its other end a spring cap, a coupling connecting the spring cap and post, the coupling comprising separable members, one fixed to the spring cap and the other to the post, the members of said coupling being separable only by a lateral movement of the spring cap relative to the post, and a coiled spring encircling the post and held between the spring base and the cap, said spring being cap-able of compression to a point in which the spring cap may be removed from the post by a relative lateral movement.

2. The structure defined in claim 1 in which the spring normally holds the spring cap against removal from the post.

3. The structure defined in claim 1 in which the members of the coupling are free to permit a limited axial movement of the spring cap relative to the post.

4. The structure defined in claim 1 in which the spring is normally held under compression between the spring base and the spring cap.

5. A spring device comprising a post having at one end a spring base, the other end portion of the post being bifurcated to afford a pair of laterally spaced upstanding prongs, a cap having a pair of depending laterally spaced prongs extending at a right angle to the prongs on the post, the lateral spacing of one pair of said prongs being such as to permit the other pair of prongs to pass therebetween by a lateral movement of the spring cap relative to the post, a coiled spring encircling the post and. held between the spring base and the cap, the pairs of prongs having opposing stop lugs holding the spring cap against axial separation from the post, said pairs of prongs and stop lugs being separable by a lateral movement of the spring cap relative to the post, said spring being capable of compression to a point below the stop lugs to permit lateral movement of the spring cap relative to the post and the separation of the same therefrom.

6. The structure defined in claim 5 in which the stop lugs are at the outer ends of the prongs and separable to permit a limited axial movement of the spring cap relative to the post.

ALBERT HOSSFELD. 

